Recent environmental problems have placed particular emphasis on filter cleaner formulations and their constituents that are biodegradable, safer to handle, and are storage stable. Biodegradability is defined as that property possessed by a material which is capable of being decomposed by bacteria or living organisms, as described, for example, in U.S. Pat. No. 3,382,285 to Egan et al.
The build-up of residue material on filters used in swimming pools and spas occurs when the pores or spaces in the filter become fouled or clogged, and this can cause undesirable high pressures in the filtration system and ultimately compromises the disinfection of the water. Residue materials which can so clog or foul a filtration system include organic residues, such as plant matter, oils and greases from swimmers, sun tan lotion and other cosmetics, and inorganic material such as calcium and magnesium salts which are found in hard water.
Many filter cleaners available today are based on strong acids such as hydrochloric and sulfuric acid or on phosphates such as trisodium phosphate, sodium tripolyphosphate and tetrapotassium pyrophosphate. In addition many of the prior art cleaning formulations contain ingredients such as non-biodegradable surfactants or detergents which persist in the environment after being used or, like phosphates, may promote undesirable growth of algae.
Illustrative of the prior art cleaner formulations are those disclosed in U.S. Pat. No. 4,965,009 to Bauer et al. This describes non-biodegradable acidic cleaner formulations containing a thickener used to treat hard surfaces so that the viscosity of the cleaning formulation will prevent it from running too rapidly off the surface to be cleaned. See also U.S. Pat. No. 4,136,025 to Zwack et al., which discloses a method of cleaning a membrane that has been used in the treatment of cataphoretic paint containing lead with an acid that forms a water-soluble lead salt and a water-soluble organic solvent.